Topology Seminar

Title: The signature modulo 8 of a fiber bundle.
Speaker: Carmen Rovi
Speaker Info: Indiana University
Brief Description:
Special Note:

In this talk we shall be concerned with the residues modulo 4 and modulo 8 of the signature of a 4k-dimensional geometric Poincare complex. I will explain the relation between the signature modulo 8 and two other invariants: the Brown-Kervaire invariant and the Arf invariant. In my thesis I applied the relation between these invariants to the study of the signature modulo 8 of a fiber bundle, showing in particular that the non-multiplicativity of the signature modulo 8 is detected by an Arf invariant. In 1973 Werner Meyer used group cohomology to show that a surface bundle has signature divisible by 4. I will discuss current work with David Benson, Caterina Campagnolo and Andrew Ranicki where we are using group cohomology and representation theory of finite groups to detect non-trivial signatures modulo 8 of surface bundles.‚Äč
Date: Monday, May 01, 2017
Time: 4:10pm
Where: Lunt 104
Contact Person: Prof. John Francis
Contact email: jnkf@math.northwestern.edu
Contact Phone: 847-491-5544
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